Project Summary Alcohol and marijuana are the most commonly used psychoactive substances among college students in the US and research has documented many acute and long-term negative consequences of high-risk use. Nearly all of the published research on college student drinking and marijuana use focuses on 4-year college students, despite statistics that students attending 2-year community colleges make up a large and growing proportion of college students in the US and that many community college students engage in high-risk alcohol and marijuana use and experience substance-related problems. The development of alcohol and marijuana interventions are warranted for community college students engaging in high-risk use, however, there needs to be a better understanding of risk factors associated with use among this particular population to identify/adapt targets of intervention. Prior research suggests that perceived descriptive and injunctive alcohol and marijuana norms are among the strongest predictors of alcohol and marijuana use and personalized normative feedback interventions have been used as stand-alone alcohol interventions and as part of multi-component brief motivational interventions to reduce normative misperceptions of peer substance use and approval of use. Social psychology and higher education theories (i.e., Social Identity Theory and Student Involvement Model) suggest identity and student connectedness are important factors to consider in the relationship between social norms and behavior. Using a mixed methods research design, the specific aims of this application are: (1) qualitatively explore social and educational identity, school connectedness, and perceived peer alcohol and marijuana use among a diverse sample of community college students, (2) conduct finite mixture modeling to identify distinct classes of alcohol and marijuana use and consequences and important correlates of identified classes among young adult community college students, (3) use longitudinal survey data with multilevel analyses to examine short- and longer-term consequences of use, as well as (4) cross-sectional and prospective associations between norms and use and potential moderators of these associations among a diverse sample of young adult community college students. The proposed study addresses an important gap in substance use research and intervention by examining an often ignored population. The applicant will also receive advanced training in: (1) etiology, prevention, and treatment of young adult substance use and scientific aspects of study management, (2) qualitative and mixed method research methods and advanced statistical methods, (3) interventions and applied work for young adult substance use, and (4) scientific writing and dissemination.